U.S. patent application number 12/133988 was filed with the patent office on 2008-10-16 for passive and active up-drill features on fixed cutter earth-boring tools and related methods.
Invention is credited to Robert J. Buske, Kenneth E. Gilmore, James L. Overstreet, John H. Stevens.
Application Number | 20080251297 12/133988 |
Document ID | / |
Family ID | 41398840 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080251297 |
Kind Code |
A1 |
Overstreet; James L. ; et
al. |
October 16, 2008 |
PASSIVE AND ACTIVE UP-DRILL FEATURES ON FIXED CUTTER EARTH-BORING
TOOLS AND RELATED METHODS
Abstract
Earth-boring tools include at least one up-drill feature
disposed on a transition surface so as to be passive during down
drilling and active during up drilling and/or back reaming
operations. Systems for down drilling and up drilling with drill
bits comprising one or more up-drill features are also disclosed.
Furthermore, methods for forming a borehole with an earth-boring
tool including such up-drill features and for forming an
earth-boring tool comprising such up-drill features are also
disclosed.
Inventors: |
Overstreet; James L.;
(Tomball, TX) ; Buske; Robert J.; (The Woodlands,
TX) ; Gilmore; Kenneth E.; (Cleveland, TX) ;
Stevens; John H.; (Spring, TX) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
41398840 |
Appl. No.: |
12/133988 |
Filed: |
June 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11685898 |
Mar 14, 2007 |
|
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12133988 |
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Current U.S.
Class: |
175/374 ; 175/57;
76/108.2 |
Current CPC
Class: |
E21B 10/43 20130101;
E21B 7/28 20130101; E21B 17/1092 20130101; E21B 10/003
20130101 |
Class at
Publication: |
175/374 ; 175/57;
76/108.2 |
International
Class: |
E21B 10/00 20060101
E21B010/00; E21B 1/00 20060101 E21B001/00; B21K 5/04 20060101
B21K005/04 |
Claims
1. An earth-boring tool, comprising: a body comprising an outer
diameter and a shank; at least one transition surface positioned
between the outer diameter and the shank; and at least one up-drill
feature disposed on the transition surface, the at least one
up-drill feature positioned to be passive during down drilling and
active during up drilling or back reaming.
2. The earth-boring tool of claim 1, wherein the at least one
up-drill feature comprises a material selected from the group
consisting of at least one of hardfacing, carbide, boride, diamond,
and diamond impregnated materials.
3. The earth-boring tool of claim 1, wherein the body is comprised
of at least one material selected from the group consisting of a
metal, a metal alloy, an infiltrated particle-matrix composite, and
a non-infiltrated particle-matrix composite.
4. The earth-boring tool of claim 1, wherein the body further
comprises a face at a distal end thereof and a gage region near a
proximal end thereof, the gage region defining the outer diameter
and comprising longitudinally upward extensions of a plurality of
blades.
5. The earth-boring tool of claim 1, wherein the at least one
transition surface comprises a chamfer.
6. The earth-boring tool of claim 1, wherein the at least one
up-drill feature extends an entire length of the at least one
transition surface.
7. The earth-boring tool of claim 1, wherein a radially outermost
surface of the at least one up-drill feature is at least
substantially flush with the outer diameter.
8. The earth-boring tool of claim 1, wherein the at least one
up-drill feature comprises a thickness of about 0.10 inch or
more.
9. The earth-boring tool of claim 1, wherein the at least one
up-drill feature comprises a plurality of up-drill features.
10. The earth-boring tool of claim 9, wherein at least some of the
up-drill features of the plurality comprise at least one of
differing thicknesses and differing shapes.
11. The earth-boring tool of claim 9, wherein the plurality of
up-drill features are positioned adjacent each other in at least
one of a rotational direction of the earth-boring tool and in a
direction from a proximal end of the at least one transition
surface toward a distal end of the at least one transition
surface.
12. The earth-boring tool of claim 1, wherein the at least one
up-drill feature extends diagonally across the at least one
transition surface.
13. The earth-boring tool of claim 1, wherein the at least one
up-drill feature comprises at least one tooth-like protrusion
therein.
14. The earth-boring tool of claim 1, further comprising an
attachment pad secured to the at least one transition surface, the
at least one up-drill feature being disposed on the attachment
pad.
15. The earth-boring tool of claim 14, wherein the attachment pad
is comprised of a material selected from the group consisting of at
least one of a metal, metal alloy, carbide, boride, diamond, and
diamond impregnated materials.
16. A system for both down drilling and up drilling with a
fixed-cutter drill bit, comprising: a body comprising at least one
top transition surface extending from an outer diameter toward a
shank and at least one up-drill feature disposed on the at least
one top transition surface; the body being operable in a down
drilling mode wherein the at least one top transition surface is
configured as passive during down drilling and portions of the bit
body distal to the at least one top transition surface are
configured as active during down drilling; and the body being
operable an up drilling mode wherein the at least one top
transition surface is configured as active during up drilling or
back reaming.
17. The system of claim 16, wherein the at least one up-drill
feature comprises a material selected from the group consisting of
at least one of hardfacing, carbide, boride, diamond, and diamond
impregnated materials.
18. The system of claim 16, wherein the body is comprised of at
least one of a metal, a metal alloy, an infiltrated particle-matrix
composite, and a non-infiltrated particle-matrix composite.
19. The system of claim 16, wherein the body further comprises a
face that defines a distal end of the body, at least one blade
disposed over a portion of the face, and a gage region defined by a
portion of the blade at a proximal end thereof, the gage region
forming the outer diameter.
20. The system of claim 16, wherein the at least one up-drill
feature comprises a thickness of about 0.10 inch or more.
21. The system of claim 16, wherein the at least one up-drill
feature comprises a plurality of up-drill features.
22. The system of claim 21, wherein at least some of the up-drill
features of the plurality comprise at least one of differing
thicknesses and differing shapes.
23. The system of claim 21, wherein the plurality of up-drill
features are positioned at least one of rotationally adjacent to
each other and adjacent in a direction from the proximal end of the
gage region toward the distal end of the shank.
24. The system of claim 16, wherein the at least one up-drill
feature extends diagonally across the at least one transition
surface.
25. The system of claim 16, wherein the at least one up-drill
feature comprises at least one tooth-like protrusion therein.
26. The system of claim 16, further comprising an attachment pad
secured to the at least one top transition surface, the at least
one up-drill feature being disposed on the attachment pad.
27. A method of forming a bore hole in a subterranean formation,
comprising: down drilling through a subterranean formation with an
earth-boring tool comprising: a body comprising at least one top
transition surface extending from an outer diameter to a distal end
of a thread shoulder; and at least one up-drill feature disposed on
the at least one top transition surface; wherein the at least one
up-drill feature is passive; and up drilling in the bore hole with
the earth-boring tool, wherein the at least one up-drill feature
engages and cuts through formation material.
28. The method of claim 27, wherein down drilling through a
subterranean formation with an earth-boring tool comprising at
least one up-drill feature comprises down drilling through a
subterranean formation with an earth-boring tool comprising at
least one up-drill feature comprising a material selected from the
group consisting of at least one of hardfacing, carbide, boride,
diamond, and diamond impregnated materials.
29. The method of claim 27, wherein down drilling through a
subterranean formation with an earth-boring tool comprising a body
comprises down drilling through the subterranean formation with the
earth-boring tool comprising a body further comprising a face at a
distal end thereof and gage regions near a proximal end thereof,
the gage regions defining the outer diameter and comprising
longitudinally upward extensions of a plurality of blades.
30. A method of forming a fixed-cutter drilling tool, comprising:
forming a body comprising an active region and a passive region in
a down drilling mode, the active region comprising portions of the
body distal to a transition edge and the passive region comprising
portions of the body proximal to the transition edge, wherein the
passive region is active in an up drilling mode; and disposing at
least one up-drill feature on the passive region.
31. The method of claim 30, wherein forming the body comprising an
active region and a passive region comprises forming a portion of
the passive region as at least one top transition surface extending
from the transition edge toward a shank.
32. The method of claim 31, wherein disposing the at least one
up-drill feature on the passive region comprises disposing the at
least one up-drill feature to extend an entire length of the at
least one top transition surface.
33. The method of claim 31, wherein disposing the at least one
up-drill feature on the passive region comprises disposing the at
least one up-drill feature diagonally across the at least one top
transition surface.
34. The method of claim 30, wherein disposing the at least one
up-drill feature comprises disposing the at least one up-drill
feature comprising a material selected from the group consisting of
at least one of hardfacing, carbide, boride, diamond, and diamond
impregnated materials.
35. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises disposing the at
least one up-drill feature such that a radially outermost edge
thereof is at least substantially flush with the transition
edge.
36. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises disposing the at
least one up-drill feature by welding or brazing.
37. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises disposing the at
least one up-drill feature with a thickness of at least
substantially 0.10 inch or more.
38. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises disposing a
plurality of up-drill features on the passive region.
39. The method of claim 38, wherein disposing a plurality of
up-drill features on the passive region further comprises
configuring up-drill features of the plurality of up-drill features
with at least one of differing thicknesses and differing
shapes.
40. The method of claim 30, further comprising forming at least one
tooth-like protrusion in the at least one up-drill feature.
41. The method of claim 40, wherein forming at least one tooth-like
protrusion comprises at least one of disposing the at least one
up-drill feature in such a manner as to form at least one
tooth-like protrusion, machining a portion of the at least one
up-drill feature into the shape of the at least one tooth-like
protrusion, and molding the at least one up-drill feature to
comprise the shape of the at least one tooth-like protrusion.
42. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises: disposing the at
least one up-drill feature on an attachment pad; and securing the
attachment pad to the passive region.
43. The method of claim 42, wherein disposing the at least one
up-drill feature on an attachment pad comprises disposing the at
least one up-drill feature on the attachment pad comprised of a
material selected from the group consisting of at least one of
metal, metal alloy, carbide, boride, diamond, and diamond
impregnated materials.
44. The method of claim 30, wherein disposing the at least one
up-drill feature on the passive region comprises: forming the at
least one up-drill feature integrally with an attachment pad; and
securing the at least one up-drill feature and integral attachment
pad to the passive region.
45. The method of claim 30, further comprising removing material
from the passive region of the body to form at least one cavity,
the at least one up-drill feature being disposed within at least a
portion of the at least one cavity and extends out of the at least
one cavity above an original surface of the body.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 11/685,898, filed Mar. 14, 2007, the
disclosure of which application is incorporated herein by reference
in its entirety.
TECHNICAL FIELD
[0002] Embodiments of the present invention relate generally to
earth-boring tools and, more particularly, to earth-boring tools
comprising passive and active up-drill protective and cutting
features.
BACKGROUND
[0003] Drilling wells for oil and gas production conventionally
employs longitudinally extending sections, or so-called "strings,"
of drill pipe to which, at one end, is secured a drill bit of a
larger diameter. The drill bit conventionally forms a bore hole
through the subterranean earth formation to a selected depth.
Generally, after a selected portion of the bore hole has been
drilled, the drill bit is removed from the bore hole so that a
string of tubular members of lesser diameter than the bore hole,
known as casing, can be placed in the bore hole and secured therein
with cement. Therefore, drilling and casing according to the
conventional process typically requires sequentially drilling the
bore hole using drill string with the drill bit attached thereto,
removing the drill string and drill bit from the bore hole, and
disposing and cementing a casing into the bore hole.
[0004] Rotary drill bits are commonly used for drilling such bore
holes or wells. One type of rotary drill bit is the fixed-cutter
bit (often referred to as a "drag" bit), which typically includes a
plurality of cutting elements secured to a face region of a bit
body. Referring to FIG. 1, a conventional fixed-cutter rotary drill
bit 100 includes a bit body 110 having a face 120 defining a
proximal end and comprising generally radially extending blades
130, forming fluid courses 140 therebetween extending to junk slots
150 between circumferentially adjacent blades 130. Bit body 110 may
comprise a composite matrix or a steel body, both as known in the
art.
[0005] The drill bit includes an outer diameter 155 defining the
radius of the wall surface of a bore hole. The outer diameter 155
may be defined by a plurality of gage regions 160, which may also
be characterized as "gage pads" in the art. Gage regions 160
comprise longitudinally upward (as the drill bit 100 is oriented
during use) extensions of blades 130. The gage regions 160 may have
wear-resistant inserts and/or coatings, such as hardfacing
material, tungsten carbide inserts natural or synthetic diamonds,
or a combination thereof, on radially outer surfaces 165 thereof as
known in the art to inhibit excessive wear thereto so that the
design borehole diameter to be drilled by the drill bit is
maintained over time.
[0006] A plurality of cutting elements 180 is conventionally
positioned on each of the blades 130. Generally, the cutting
elements 180 have either a disk shape or, in some instances, a more
elongated, substantially cylindrical shape. The cutting elements
180 commonly comprise a "table" of super-abrasive material, such as
mutually bound particles of polycrystalline diamond, formed on a
supporting substrate of a hard material, conventionally cemented
tungsten carbide. Such cutting elements are often referred to as
"polycrystalline diamond compact" (PDC) cutting elements or
cutters. The plurality of PDC cutting elements 180 may be provided
within cutting element pockets 190 formed in rotationally leading
surfaces of each of the blades 130. Conventionally, a bonding
material such as an adhesive or, more typically, a braze alloy may
be used to secure the cutting elements 180 to the bit body 110.
[0007] The bit body 110 of a rotary drill bit 100 typically is
secured to a steel shank 200 having an American Petroleum Institute
(API) thread connection for attaching the drill bit 100 to a drill
string (not shown). Top transition surfaces 210 are located at the
upper ends of the gage regions 160 between the outer diameter
defined by the radially outer surfaces 165 of gage regions 160 and
a shank shoulder 220. Transition edges 230 are defined between the
radially outer surfaces 165 of gage regions 160 and their
respective, associated top transition surfaces 210.
[0008] During drilling operations, the drill bit 100 is positioned
at the bottom of a well bore hole and rotated. Drilling fluid is
pumped through the inside of the bit body 110, and out through
nozzles (not shown). As the drill bit 100 is rotated, the PDC
cutting elements 180 scrape across and shear away the underlying
earth formation material. The formation cuttings mix with the
drilling fluid and pass through the fluid courses 140 and then
through the junk slots 150, up through an annular space between the
wall of the bore hole and the outer surface of the drill string to
the surface of the earth formation.
[0009] When drilling in unconsolidated, highly abrasive and/or
hardened formations as well as in other formation materials, the
radially outer surface of the gage regions 160 of the drill bits
are subjected to wear caused by the abrasive cuttings being
drilled, the high sand content in the mud, and the sand particles
along the borehole wall. Improvements in the wear-resistant inserts
and/or coatings have helped to limit the accelerated wear from
occurring to the radially outer surfaces 165 of the gage regions
160 in the normal (i.e., downward) drilling mode. However, when the
drill bit 100 is reversed in the bore hole, such as when back
reaming or up drilling is performed, substantial wear to the top
transition surfaces 210 including the transition edges 230 located
near the shank 200 end of the bit may occur. Such wear causes
rounding over the gage region 160 and eventually will significantly
wear the gage region 160.
BRIEF SUMMARY
[0010] Various embodiments of the present invention are directed
toward a fixed-cutter drilling tool configured for down drilling
and up drilling through subterranean formation and for limiting the
accelerated wear from occurring to the passive regions. In one
embodiment, the present invention comprises a body comprising an
outer diameter and secured to a shank. At least one transition
surface may be associated with and positioned between the outer
diameter of the body and the lower extent of the shank. At least
one up-drill feature may be disposed on the at least one transition
surface and may be positioned to be passive (not engage the
formation being drilled) during down drilling and active during up
drilling, back reaming, or other similar activities.
[0011] In another embodiment, the present invention contemplates a
system for both down drilling and up drilling with a fixed-cutter
drill bit. The system may comprise a bit body comprising a face
that defines a distal end. At least one blade may be disposed over
a portion of the face and may, at a proximal end thereof, define a
gage region. At least one top transition surface may extend from a
radially outer surface at a proximal end of the gage region toward
a distal end of a shank secured to the bit body, and at least one
up-drill feature may be disposed on the at least one top transition
surface. The system may comprise a down drilling mode in which,
while down drilling, the at least one top transition surface is
configured as passive and portions of the bit body distal to the at
least one top transition surface are configured as active.
Furthermore, the system may comprise an up drilling mode in which,
during up drilling or back reaming, the at least one top transition
surface is configured as active.
[0012] In yet another embodiment, the present invention comprises a
method of forming a bore hole. The method may comprise down
drilling through a formation with an earth-boring tool. The
earth-boring tool may comprise a body comprising a face at a distal
end thereof and a gage region near a proximal end thereof, the gage
region comprising longitudinally upward extensions of a plurality
of blades. At least one top transition surface may extend from a
proximal end of the gage region toward a distal end of the bit
shank. Furthermore, at least one up-drill feature may be disposed
on the at least one top transition surface, the at least one
up-drill feature being passive during the down drilling. The method
may further comprise up drilling in the bore hole with the
earth-boring tool, wherein the at least one up-drill feature
engages and cuts through some of the formation.
[0013] In another embodiment, the present invention contemplates a
method of forming a fixed-cutter drilling tool. The method may
comprise forming a body comprising an active region and a passive
region in a down drilling mode. The active region may comprise
portions of the body distal to a transition edge while the passive
region may comprise portions of the body proximal to the transition
edge. The body may be configured so that the passive region is
active when the body is in an up drilling mode. The method further
comprises disposing at least one up-drill feature on the passive
region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates an elevation view of a conventional
fixed-cutter earth-boring rotary drill bit;
[0015] FIG. 2 is an enlarged elevation view of an earth-boring
drill bit including an up-drill feature positioned on a top
transition surface according to an embodiment of the invention;
[0016] FIG. 3 is an enlarged partial side view of the drill bit of
FIG. 2;
[0017] FIG. 4 is an enlarged elevation view illustrating a
plurality of up-drill features on a top transition surface of an
earth-boring drill bit according to an embodiment of the
invention;
[0018] FIG. 5 illustrates a magnified elevation view of a blade and
top transition surface including a plurality of up-drill features
comprising differing general thicknesses according to an embodiment
of the invention;
[0019] FIGS. 6 and 7 show a plurality of up-drill features
extending diagonally across the top transition surface;
[0020] FIG. 8 illustrates an embodiment in which one or more of the
up-drill features comprises at least one tooth-like protrusion
therein; and
[0021] FIG. 9 illustrates an up-drill feature pad comprising at
least one up-drill feature and positionable on a passive portion of
the bit body.
DETAILED DESCRIPTION
[0022] The illustrations presented herein are, in some instances,
not actual views of any particular up-drill features or drill bit,
but are merely idealized representations which are employed to
describe the present invention. Additionally, elements common
between figures may retain the same numerical designation.
[0023] Embodiments of the present invention provide an earth-boring
tool comprising features capable of providing wear protection
and/or cutting formation material during up drilling, back reaming,
and other similar procedures. Referring to FIG. 2, an enlarged view
of a top transition surface 210 of an earth-boring drill bit is
shown. The drill bit of FIG. 2 may be a fixed-cutter rotary drill
bit similar to the drill bit 100 of FIG. 1. As described above with
reference to FIG. 1, the earth-boring drill bit 100 includes a bit
body 110 comprising one or more top transition surfaces 210 located
between the outer diameter 155 and the shank shoulder 220. In some
embodiments, the top transition surface 210 may comprise a chamfer,
e.g., the surface may lie at an oblique angle to the longitudinal
axis of the earth-boring drill bit 100. The earth-boring drill bit
100 may further comprise a face 120 at a distal end thereof having
one or more blades 130 extending generally radially therefrom and
continuing to extend generally longitudinally upward along the bit
body 110 to form a gage region 160 near a proximal end thereof. The
radially outer surface 165 of gage region 160 may define the outer
diameter 155 such that the top transition surface 210 may be
associated with the proximal end of the gage region 160. The top
transition surface 210 may extend from the proximal end of the gage
region 160, defined by the transition edges 230, toward the shank
200 and may, optionally, extend to a distal end of the shank
shoulder 220.
[0024] The drill bit 100 may be operated in a conventional
down-drilling mode wherein regions or portions of the bit body that
are distal to (i.e., below, in vertical drilling) the top
transition surfaces 210, and more particularly, to the transition
edges 230, are defined as "active" and may engage as well as cut
formation material during down drilling and wherein regions or
portions of the bit body 110 that are proximal to (i.e., above) the
gage region 160, and more particularly, the transition edges 230,
and radially inboard of the outermost radius defined by the gage
region 160 are defined as "passive" (i.e., does not intentionally
engage the formation or cut formation material) during down
drilling. The drill bit 100 also may be operated in an up drilling
mode, wherein the regions or portions of the bit body 110 that are
proximal to the gage region 160, and which are passive during down
drilling, are active during up drilling or back reaming.
Accordingly, the portions that are active during down drilling
typically become passive during up drilling.
[0025] The drill bit 100 also comprises an up-drill feature 240
strategically located on the passive portions of the bit body 110.
In some embodiments, the up-drill feature 240 may comprise
metallurgically bonded hardfacing or a carbide material and may be
similar to those features of U.S. application Ser. No. 11/685,898,
referred to herein above and described therein as "hardfacing",
such as hardfacing 61, 71, 81, 91, 101, 111, and/or 121. The
up-drill feature 240 is configured for cutting formation material
and providing wear protection for the bit body 110 during up
drilling or back reaming. Accordingly, the up-drill feature 240 is
disposed on portions of the bit body 110 generally located axially
above the transition edges 230, and radially inward of the maximum
outer diameter of the drill bit 100 (e.g., at the gage region 160).
As illustrated in FIGS. 2 and 3, the up-drill feature 240 may be
located on the top transition surfaces 210, extending from a
position adjacent to the transition edge 230 toward the shank
shoulder 220, the radially outermost edge of the up-drill feature
240 being, in some embodiments, at least substantially flush with
the gage region 160. In some embodiments, the up-drill feature 240
extends the entire length from the transition edge 230 to the shank
shoulder 220, while in other embodiments the up-drill feature 240
extends only a portion of the length between the transition edge
230 and the shank shoulder 220.
[0026] The up-drill feature 240 may comprise hardfacing material
having a thickness of about 0.10 inches or more, as measured from
the transition surface 210 itself. In another embodiment, the
hardfacing material may comprise a thickness of 0.25 inches or
more. The hardfacing material itself may comprise iron or
nickel-based materials. By way of example and not limitation, the
hardfacing material may include a matrix of Ni--Cr--B--Si with
spherical cast WC pellets, and/or spherical sintered WC pellets.
Another non-limiting example may include an iron matrix, again with
spherical WC pellets, spherical cast WC pellets, crushed sintered
WC, and/or crushed cast WC granules or any combination thereof. The
hardfacing may be applied using a welding process. Such processes
for application of the hardfacing to oil field tools are generally
known to those of ordinary skill in the art and may include
oxy-acetylene, MIG, TIG, SMA, SCA, PTA, etc. Furthermore, welding
may include employing a pulsed arc as well as a constant arc. In
some embodiments, the hardfacing may be mechanically shaped, such
as by machining, after it is applied to form specific features
and/or configurations in the hardfacing material.
[0027] In other embodiments, the up-drill features 240 may be
preformed from another suitable material, such as, for example
carbides or borides of one or more of W, Ti, Mo, Nb, V, Hf, Ta, Cr,
Zr, Al, or Si, diamond (natural or synthetic), and diamond
impregnated material. In such embodiments, the preformed up-drill
feature 240 may comprise similar thicknesses as the hardfacing
material. The up-drill feature 240 comprising one or more of these
other suitable materials may be attached to the passive portion of
the bit body 110. For example, the up-drill feature 240 may be
brazed, welded or otherwise secured to the bit body. In some
embodiments, the up-drill feature 240 may further be at least
substantially covered in a hardfacing material. Such a
configuration may be beneficial to form specific features into the
up-drill features 240, such as those described in more detail
below. For example, a specific feature may be formed by molding or
otherwise performing the up-drill feature 240 and then hardfacing
material may be disposed over the preformed up-drill feature 240 in
such a manner so as to at least substantially retain those external
features formed in the preformed up-drill feature 240.
[0028] In some embodiments, the drill bit 100 may comprise a
plurality of up-drill features 240 on portions of the bit body 110.
FIG. 4 illustrates an embodiment of a drill bit 100 comprising a
plurality of up-drill features 240 on the top transition surface
210. In this embodiment, the plurality of up-drill features 240 may
be at least substantially similar in thickness and shape and may
also extend across the top transition surface 210 in at least
substantially the same manner. The drill bit 100 may include a
sufficient number of up-drill features 240 to cover at least
substantially all of the top transition surfaces 210, while in
other embodiments a single up-drill feature 240 may be configured
to cover at least substantially the entire top transition surface
210. In the embodiments shown in FIG. 4, the plurality of up-drill
features 240 are positioned rotationally adjacent to one another.
Alternatively, or in addition, a plurality of up-drill features 240
may be positioned adjacent one another in the direction from the
transition edges 230 to the shank shoulder 220.
[0029] In other embodiments, the plurality of up-drill features 240
may comprise differing thicknesses and/or differing shapes. As
shown in FIG. 5, a first up-drill feature 240' may have a general
thickness which differs from the thickness of a second up-drill
feature 240''. As used herein, the term "thickness" of an up-drill
feature generally indicates its distance above a portion of the
drill bit to which it is disposed, for example the distance above
the top transition surface.
[0030] In some embodiments, the one or more up-drill features 240
may be disposed over the top transition surfaces 210 extending
diagonally from the transition edge 230 toward the shank shoulder
220. FIG. 6 shows an embodiment in which the one or more up-drill
features 240 extend diagonally to the left across the top
transition surfaces 210. FIG. 7 shows an embodiment in which the
one or more up-drill features 240 extend diagonally to the right
across the top transition surface 210.
[0031] The one or more up-drill features 240 may include one or
more specific features configured according to the specific
application of the drill bit 100. In some embodiments, the one or
more specific features may be formed by applying the hardfacing in
such a manner as to form a desired shape and/or contour. In other
embodiments, the one or more specific features may be formed by
machining the desired shape and/or contour into the hardfacing
comprising the one or more up-drill features 240. In still other
embodiments, when the up-drill features 240 comprise a carbide
material, the one or more specific features may be formed by
machining or molding the carbide. By way of example and not
limitation, in one embodiment shown in FIG. 8, the one or more
up-drill features 240 may be configured to include at least one
feature configured as a tooth-like protrusion 250 therein. The
tooth-like protrusion 250 may be further configured to comprise a
back rake, side rake, or chamfer in accordance with the specific
application. Such tooth-like protrusions 250 may be combined with
any of the above described embodiments. For example, in embodiments
comprising more than one up-drill feature 240, at least one
up-drill feature 240 may comprise at least one tooth-like
protrusion 250 while at least one other up-drill feature 240 may
not include any tooth-like protrusion 250.
[0032] Still other designs for the up-drill feature 240 include
additionally strategic up-drill feature placement and
configurations, graded composite hardfacing materials, various
carbide materials, recesses or cavities at edges of the outer
diameter, and various methods of applying the material also may be
employed. Moreover, material may be removed from portions of the
bit body to form cavities. In one embodiment, the cavities may be
backfilled with hardfacing and comprise additional hardfacing
extending out of the cavities above an original surface of the bit
body to form up-drill features. In other embodiments, a carbide
up-drill feature 240 may be attached, e.g., brazed, to the bit body
within the cavities.
[0033] FIG. 9 illustrates another embodiment of the present
invention comprising an attachment pad 260 comprising at least one
up-drill feature 240 formed thereon. The attachment pad 260 is
configured to be positioned on a portion of the bit body 110. For
example, the attachment pad 260 may be sized and configured to be
positioned on at least a portion of a top transition surface 210.
In some embodiments, the attachment pad 260 may comprise a pad to
which one or more up-drill features 240 are secured. The attachment
pad 260 may comprise a material such as, for example, metal or
metal alloy, carbides or borides of one or more of W, Ti, Mo, Nb,
V, Hf, Ta, Cr, Zr, Al, or Si, diamond (natural or synthetic), and
diamond impregnated material. The at least one up-drill feature 240
may comprise any of those materials described herein above with
relation to embodiments of the up-drill features 240. In the case
of a preformed up-drill feature 240, such as those described herein
above, the one or more up-drill features 240 may be secured to the
attachment pad 260 by employing those methods known to those of
ordinary skill in the art. In other embodiments, the attachment pad
260 and the one or more up-drill features 240 may comprise an
integral structure. In such embodiments, the pad 260 and the one or
more up-drill features 240 may comprise a material similar to those
materials described above with relation to the preformed up-drill
features 240, such as carbide, boride, diamond (natural or
synthetic), diamond impregnated material or other suitable material
or combinations thereof. By way of example and not limitation, the
one or more up-drill features 240 and attachment pad 260 may be
formed by molding the up-drill features 240 with the desired shape
and the attachment pad 260 as an integral structure. The attachment
pad 260 may be brazed, welded or otherwise secured to the passive
portion of the bit body 110, such methods being generally known to
those of ordinary skill in the art.
[0034] Earth-boring tools according to embodiments of the present
invention may be employed to form a bore hole in a subterranean
formation. An earth-boring tool may be connected to a drill string
and may down drill through subterranean formation to form a bore
hole therein. The earth-boring tool may be configured according to
any of the embodiments described herein above, and includes at
least one up-drill feature 240 positioned on a portion of the
earth-boring tool. The earth-boring tool may further be used to up
drill in the bore hole. As the earth-boring tool up drills in the
bore hole, the at least one up-drill feature 240 is configured and
positioned as active and directly engages and cuts through some of
the formation. As used herein, the term "earth boring tool"
includes and encompasses conventional fixed cutter bits including
core bits, bicenter bits, eccentric bits, fixed cutter reamers such
as, for example, so-called "reamer wings," and other drilling tools
having a suitable surface or surfaces for disposition of an
up-drill feature of an embodiment of the invention thereon.
[0035] The present invention has utility in relation to
fixed-cutter drill bits and other drilling tools having bodies at
least substantially comprised of a metal or metal alloy such as
steel, but also has utility in bits and tools having bodies at
least substantially comprised of particle-matrix composite
materials, including conventional infiltrated composite bodies as
well as non-infiltrated composite bodies. Conventional infiltrated
composite bodies include those in which hard particles (e.g.,
tungsten carbide) are infiltrated by a molten liquid metal matrix
material (e.g., a copper-based alloy) within a mold.
Non-infiltrated composite bodies may include, for example,
"sintered" particle matrix bits in which a powder metal (e.g.,
nickel or cobalt powder) is mixed with a powder comprising hard
particles (e.g., tungsten carbide) and, thereafter, pressed and
sintered to a final density. An example of sintered particle matrix
bodies include those disclosed in pending U.S. patent application
Ser. No. 11/271,153, filed Nov. 10, 2005 and pending U.S. patent
application Ser. No. 11/272,439, also filed Nov. 10, 2005, the
disclosure of each of which application is incorporated herein in
its entirety by this reference.
[0036] While certain embodiments have been described and shown in
the accompanying drawings, such embodiments are merely illustrative
and not restrictive of the scope of the invention, and this
invention is not limited to the specific constructions and
arrangements shown and described, since various other additions and
modifications to, and deletions from, the described embodiments
will be apparent to one of ordinary skill in the art. Thus, the
scope of the invention is only limited by the literal language, and
legal equivalents, of the claims which follow.
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